bút

Být is the Czech verb meaning "to be." It is a foundational and highly frequent verb that functions as a copula in equative clauses and as an auxiliary in compound tenses and passive constructions. The infinitive is být.

Conjugation and key forms are irregular and cover several tenses and moods. Present indicative forms are: já jsem, ty jsi, on/ona/ono je, my jsme, vy jste, oni jsou. The imperative is buď for singular and buďte for plural. The past tense has gender- and number-specific forms: masculine singular byl, feminine singular byla, neuter singular bylo; masculine plural byli, feminine/plural byly. The future tense in Czech is analytic and formed with the present tense of být: budu, budeš, bude, budeme, budete, budou. The conditional mood is built with by and the past participle, for example byl bych, byla bych, byli bychom.

Usage and functions. Být serves as a copula linking subject and predicate.

- As a copula in present: To je dům. In past: Dům byl starý.

- As an auxiliary in compound tenses and the passive voice: Dům byl postaven.

- In weather and existential expressions: Bude pršet. Zítra bude hezky.

- In hypothetical or conditional contexts: Chtěl bych být doma.

Etymology. The Czech bý­t derives from Proto-Slavic *byti, with cognates in related Slavic languages (for example Polish być, Russian быть). It is part of a broad Indo-European family of “be” verbs and underpins everyday speech across tenses, moods, and constructions.